Manufacture of electric filament.



CARL AUER VON WELSBACH, OF VIENNA, AUSTRIA-HUNGARY, ASSIGNOR TOWELS-BACH LIGHT COMPANY, OF GLOUCESTER NEW JERSEY.

CITY, NEW JERSEY, A CORPORATION OF MANUFACTURE OF ELECTRIC FILAMENT.

No Drawing.

To all whom it may concern:

Be it known that I, Dr. CARL AUER VON WELSBACH, va subject ofthe Emperorof Austria-Hungary, residing at Vienna,' Austria-Hungary, have inventedor discovered a new and useful Improvement in the Manufacture ofElectric Filaments, of which the following is a specification.

The object of my invention is to produce a filament substantially ofosmium; another object is to provide a method of obtaining such afilament, and to this end to cover a platinumor other suitable wire witha coherent compact layer of 'osmium or an alloy thereof of, suflicientthickness of a homogenous character of requisite flexibility.

In the practice of. my invention I produce upon a platinum or suitablewire a number of superposed layers of osmium or a compound thereof.Subsequently the platinum or other wire is caused to form an alloy withthe coating containing osmium. Afterward the platinum or other materialof the wire is volatilized in whole or in part leaving a filamentcontaining osmium or osmium alloyed with the metal of the wire. Such afilament is somewhat pliable, is homogeneous and well adapted for use inelectric incandescent-lamps.

I have obtained good results in practice by the use of a platinum wireand I will describe my invention in connection therewith.

I prepare a diluted osmium compound in the form of a solution rendered,if necessary, a little more consistent by the addition of finely dividedosmium; or another solid osmium compound like sulfid or tetra-hydroxidmay be used.- I coat the platinum wire with such solution either bymeans of a brush orother appropriate implement, or

by passing the wire through the liquid.-

The wire is repeatedly passed through the liquid and heated to thedrying point between each immersion or application until a coating ofthe desired thickness-is obtained. It may be remarked that it is bestthat each layer should be thin, so that the described operation ofsupplying each separate coat and then heating it must berepeated manytimes in order to make the filament sufficiently thick. Although it maybe accomplished with one sufliciently uniform coating application and ofa drying heat. By thus depositing the osmium coating slowly anduniformly the osmium filament finally Specification of Letters Patent.

Patented Sept. 8, 1914.

Application filed August 9, 1898. Serial No. 688,203.

color. A brittle alloy of osmium and plat-inum may result from the abovedescribed operation, but such an alloy lacks perfect homogeneity.However, by gradually increasing the heat to which the filament issubjected by the passage through it of an electric current to therequired temperature,

the platinum of the alloy mayjbc almost completely volatilized withoutfusing the alloy itself while at the same time the describedcharacteristics of the finished filament are insured. It is ofimportance that a su-fiiciently thick and uniform coating be obtainedbefore the wire is subjected to the final gradual application of theelectric current up to the production of a temperature at which the corewire will volatilize. In lieu of platinum other metals may be usedprovided they are sutliciently ductile and resist temperatures to whichthe filament is exposed in the course of its preparation, as well asother conditions to which the filament is subjected in the course of itsmanufacture.

As an example of the reducing gas to which reference has been made I mayrefer to gas obtained from the center of a Bunsen tube which is ignitedat its air inlets which contains hydrogen, carbon-monoxid andhydro-carbons, and which gas also con: talns water vapor.

One purpose of the application of hea between each. application of thedescribed coating is to reduce the coating to the metalhc state, thatis, in the resent instance to osmium. Instead of supplying osmium or.

k osmium compound in the form of a solution,

as has been referred-to, a very thin platinum which will form a kind ofemulsion of the components. Ruthenium and rhodium either in whole orpart or with osmium or its compoundsmay be used.

It will be understood that, in the method claims herein, I intend toinclude by the expressions coatings containing osmium and coatingcontaining osmium, a coating or coatings wherein osmium appears in anyof the specific forms described, e., either in the form of a compound,or in the metallic form, or as a' mixture thereof.

Having thus described my invention, what I claim is: Y

. 1. The herein-described process of making filaments for electricincandescent lamps, which consists in repeatedly applying successivecoatings containing osmium to a wire and subjecting the same to theaction of a drying heat between each coating, and then subjecting thecoated wire to the action of an electric current in a. protectiveatmosphere oxidizing as to any carbon present in the coating, until itis raised to a temperature higher than the volatilizing temperature ofits core; substantially as set forth.

2. The herein-described process of making filaments for electric lamps,which consists in repeatedly applying coatings containing osmium to awire and subjecting the same to the action of heat between each coating,and finally exposing the coated Wire in a protective atmosphereoxidizing as'to any carbon present in the coating, to a graduallyincreasing temperature which finally is greater than the volatilizingtemperature of the core; substantially as set forth.

3. The herein-described process of making filaments for electric lamps,which consists in applying coatings containing osmium to a platinum wireand finally subjecting the coated wire to the action of an electriccurrent in a protective atmosphere oxidizing as to any carbon present inthe coating, up

to a temperature beyond the volatilizing temperature of the platinum;substantially as set forth.

a. The herein-described process of making filaments for incandescentlamps, which consists in applying a coating containing osmium to a wire,then subjecting the same to a drying heat and then to a graduallyincreasing electric current in a protective atmosphere oxidizing as toany carbon present in the coating, until the temperature of the wirecore exceeds its temperature of volatilization; substantially as setforth.

5. The herein described process of making metallic filaments forincandescent lamps, consisting in coating a wire core with a coatingcontaining a metal having a point of fusion above the volatilizing pointof the wire core, then subjecting the same to a drying heat and then tothe action of the electric current, in the presence of a reducing gas,until sufiicient heat has been developed to volatilize the wire core andleave the metallic particles in a cemented or coherent condition;substantially as set forth. 6. The herein described process of makingmetallic filaments for incandescent lamps, consisting in coating a wirecore with a coating containing a metal having a point of fusion abovethe volatilizing point of the wire core, subjecting the same to a dryingheatandthen to the action of the electric current, in the presence ofthe gas obtained from a Bunsen tube ignited at its air inlets, untilsufficient heat has been developed to volatilize the wire core and leavethe metallic particles in a cemented or coherent condition;substantially as described. Signed this 27th day of July 1898.

DR. CARL AUER vomvttselcu.

,VVitnesses LUDWIG HAILIN GER, Anonr GALLIA.

